The description of the movement of bodies by their position, velocity, acceleration (and possibly higher time derivatives, such as, jerk) without concern for the underlying dynamics/forces/causes.
1
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2answers
114 views
Calculating Average Velocity
I understand that the concept of an average of a data list means finding a certain value 'x', which ensures that the sum of the deviations of the numbers on the left of 'x' and on the right of 'x' ...
0
votes
2answers
121 views
How can I add an acceleration vector to a velocity with a different direction?
I am in my last year of high school and am struggling with some homework. I'm sorry if this question is incredibly stupid, but I simply can't find the answer in my notes.
If I have an object with a ...
0
votes
2answers
143 views
Equation of motion for average acceleration
I am trying to solve the following:
A man of mass 83 kg jumps down to a concrete patio from a window ledge only 0.48 m above the ground. He neglects to bend his knees on landing, so that his ...
-3
votes
3answers
72 views
Speed of an object in air versus in vacuum
Okay, imagine that you are shooting a rocket down a tunnel that is 60 miles long and the rocket is travelling at 60mph, so the rocket should reach the end of the tunnel in a hour, right? Yep, in an ...
4
votes
1answer
45 views
How to track the visual path of a LEO satellite as seen from the ground
I have been struggling with this problem for a while so I decided to ask. I'm new here and I'm not sure where this type of question belongs, so forgive me if this isn't the right section.
I am ...
1
vote
0answers
53 views
I need help with the following Physics' questions [closed]
I need to know which formulas and the step-by-step answers for the following physics questions:
1. You throw a ball upward with an initial speed of 7.0 m/s, and it returns to your hand o.92 ...
1
vote
0answers
48 views
A 0.1kg ball of dough is thrown up with a velocity of 15m/s. What is the momentum halfway up? [closed]
I know that $p=mv$ and (0.1kg)(15m/s)=1.5 kg m/s and the momentum at the vertex is 0, but what is the momentum halfway up?
3
votes
3answers
119 views
When can one write $a=v \cdot dv/dx$?
Referring to unidimensional motion, it is obvious that it doesn't always make sense to write the speed as a function of position. Seems to me that this is a necessary condition to derive formulas ...
0
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0answers
54 views
At an acceleration of 2ft/s^2, how fast could I reach 9.8MPH? [closed]
Question title is self explanatory.
If I'm accelerating at $2ft/s ^{2}$, how long does it take to reach $9.8MPH$?
3
votes
1answer
87 views
How deep is the well, given this data?
A rock is dropped into a well. A timer starts when the rock is dropped and is stopped when the noise of the rock hitting the ground of the well is heard. How deep is the well?
Here's what I have so ...
5
votes
3answers
316 views
Why isn't average speed equal to displacement over time?
I'm in an introductory Physics course and I need help!
During a one-hour trip, a small boat travels 80.0km north and then travels 60.0km east. What is the boat's average speed during the one-hour ...
1
vote
0answers
45 views
How to calculate the correct coordinates from a distorted video of a projectile?
I am working on a high school project that is related to projectile motion. I am exploring how exactly the position of the center of mass affects the trajectory of a long but thin, javelin-like ...
0
votes
0answers
60 views
Magnitude of object's angular acceleration [closed]
I'm studying for a physics exam today and am super stumped on a problem. Would love your help, or some guidance on how to solve it.
An object is being spun at an angular speed of 4.3 rad/s and ...
0
votes
0answers
78 views
Physics about plane take off simple find the acceleration problem [closed]
This was on my test, but I kinda botched it I think.
I was trying to use
V^2f = Vo^2 + 2a(delta x)
A plane must reach 226km/h to take off. Runway is 2000m. What's minimum acceleration needed? ...
1
vote
2answers
245 views
3D: Get linear velocity from position and angular velocity
I want to find out the linear velocity of a point in 3D space, (Euclidean), given:
Its position
Its angular velocity
The point it's rotating around (fulcrum)
(This is a problem I need to solve ...
0
votes
2answers
79 views
0
votes
1answer
60 views
Is it necessary to know initial y velocity to solve this projectile motion problem?
A marble is launched horizontally off a 93.0-cm high table causing the marble to land on the floor 1.85 m from the base of the table.
a.) How long was the ball in the air?
b.) With what ...
1
vote
1answer
136 views
Projectile motion problem with upward acceleration and horizontal velocity [closed]
An electron in a cathode-ray tube is traveling horizontally at 2.10×10^9 cm/s when deflection plates give it an upward acceleration of 5.30×10^17 cm/s^2 .
B.) What is its vertical displacement during ...
0
votes
1answer
96 views
What's the difference between these two formulas and how are these called?
I just want to know the differences between these two formulas:
$h = h_0 + v_0 t ± \frac{1}{2} g t^2$
and
$y = y_0 + v_{0y} t + \frac{1}{2} g t^2$
Also, how are these called in English?
2
votes
3answers
147 views
In projectile motion, what does it mean for the motion along the $x$ and $y$ axis to be independent?
In projectile motion, what does it mean for the motion along the $x$ and $y$ axis to be independent?
This question is referring to the concept of projectile motions.
1
vote
2answers
92 views
Why does gravity assist transfer twice the planet's velocity?
In orbital mechanics and aerospace engineering a gravitational slingshot (also known as gravity assist manoeuver or swing-by) is the use of the relative movement and gravity of a planet or other ...
1
vote
1answer
178 views
Monkey and tree - projectile motion
The famous scenario: A hunter is trying to shoot a Monkey hanging from a tree. However, this question doesn't mention the monkey jumping down from the tree or trying to escape. (The hunter uses a ...
0
votes
1answer
146 views
How do I find the magnitude and angle of the velocity?
I'm confused about the following problem.
A ball is shot from the ground into the air. At a height of $9.1\text{ m}$, its velocity is $v = (7.6\hat{\imath}+ 6.1\hat{\jmath})\text{m/s}$, with ...
0
votes
0answers
20 views
Movement of a ball on a curved ramp [duplicate]
Possible Duplicate:
What is a natural movement of a ball on a upward curve (the two arrow lines pointing upward) given no external force?
http://i47.tinypic.com/mt55s7.jpg
-See for image
...
6
votes
4answers
463 views
How to brake 'beautifully'?
Sometimes when I'm driving my car, I play a "game" against myself in which I try to minimize the deceleration felt by passengers (including myself) while still braking in a reasonable short space. I ...
1
vote
1answer
143 views
Projectile motion in two and three dimensions question?
So I bought this book in the library and physics fascinates me and I found this quote in the book " Galileo has proved that when any effects due to air resistance
are ignored, the ranges for ...
0
votes
0answers
162 views
Damping force of a shock absorber
I removed a shock absorber from my car, and I have a 50 pound dumbbell, I was gonna hang the dumbbell from the shock absorber and let it drop a known distance to get velocity
From my understanding, ...
0
votes
0answers
54 views
Accelerated motions of a car and a truck [closed]
A car and a truck start from rest at the same instant with the car initially at same distance behind the truck. The truck has constant acceleration of 3.4 m/s^2. The car overtakes the truck within the ...
0
votes
2answers
108 views
Non-zero higher time derivatives of position?
My mom told me to use speed control, which would allow the car to remain at constant speed. I told her that its impossible for a car to maintain constant speed, as slight changes in friction on the ...
0
votes
5answers
257 views
How a spacecraft travelling near light speed avoid asteroids?
How would a spacecraft traveling near light speed avoid a (relatively dense group of) asteroids? Or suppose such spacecraft is designed, how would the physics work for steering it inside such a ...
0
votes
1answer
274 views
Kinetic energy in the center of mass
In a collision of a particle
of mass $m_1$ moving with speed $v_1$ with a stationary particle
of mass $m_2$ not all the original kinetic energy can be converted
into heat or internal energy. what ...
0
votes
2answers
167 views
Calculating vertical velocity component of a particle with mass, given the hit point of parabolic motion
Consider the following situation:
I have a particle with a given mass that at a given instant of time (let's say $t_{0}$) is placed at the system origin. The particle has a constant velocity ...
0
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0answers
78 views
Physics question motion in two dimensions? [closed]
A ball jumps from the plane and the ball has the acceleraion 500 m/s^2...the ball falls into the ground for 3 seconds..the speed of the plane is 500 m/s headed to east.Determine the position and the ...
1
vote
1answer
181 views
Non-commutative property of rotation
Addition of angles are non-commutative in three dimensions. Hence some other angular vector quantities like angular velocity, momentum become non-commutative. What is the physical significance of this ...
3
votes
1answer
214 views
Why is the velocity on the top of a wheel twice the velocity of its axle?
When a wheel is rolling, not skidding, and its axle moves at velocity $\vec{v}$, then a point on the top of its circumference will move at velocity $2\vec{v}$, shown below.
I really don't ...
0
votes
0answers
72 views
Downhill projectile question [closed]
I have to solve the following problem:
A hill is sloped downward at an angle $\theta$ with respect to the horizontal. A projectile of mass $m$ is fired with speed $v_0$ perpendicular to the hill. ...
0
votes
0answers
26 views
Intuitive understanding of the equation for kinetic energy [duplicate]
Possible Duplicate:
Why does kinetic energy increase quadratically, not linearly, with speed?
I know this is one of the easiest equations out there and I've used it for years but its still ...
3
votes
1answer
112 views
Is it possible to determine particles' velocities from their crossings on a ring?
2 particles are constrained to move in a ring. Both particles begin moving at $t=0$ from $p=0$, each particle moving in the opposite direction of the other. It is known that they are moving at ...
0
votes
2answers
195 views
What is the force of friction between two bodies given their masses and a force pulling them as a unit accross a surface?
Where a force of 200N pulls two blocks together(as one system) across a horizontal table top(µ=0.800)
$m_A$ = 5.00kg, $m_B$ = 10.0kg
Find the acceleration of the system.
Find f$_k$ between B and A
...
2
votes
2answers
113 views
Direction of friction on rollers with plank resting on top
In a question, its given that a plank is resting on 2 rollers like:
Then the explanation, as part of computing the forces, for the direction of friction on the rollers look like:
Why are the ...
14
votes
6answers
3k views
Is two cars colliding at 50mph the same as one car colliding into a wall at 100 mph?
I was watching a youtube video the other day where an economist said that he challenged his physics professor on this question back when he was in school. His professor said each scenario is the same, ...
0
votes
1answer
139 views
Two Different Sorts of Inertia: Inertial Mass and Moment of Inertia
There are two different sorts of inertia: inertial mass and moment of inertia.
I am currently reading about moment of inertia. Now, I know inertia is an important concept; with it, we can determine ...
0
votes
2answers
136 views
Energy Question
Carl throws 100 g of Bohrium-262 (Half life: 0.10 seconds, undergoes alpha decay) to Sukhdeep with a initial horizontal velocity of 20.0 m/s at an initial height of 2.00 m above the ground. What is ...
7
votes
5answers
440 views
How can kinetic energy be proportional to the square of velocity, when velocity is relative?
Let's start with kinetic energy (from los Wikipedias)
The kinetic energy of an object is the energy which it possesses due to its motion. It is defined as the work needed to accelerate a body of a ...
0
votes
1answer
68 views
Minimum time required to reach a point [closed]
A police inspecter P is at point $ (\acute{x},\acute{y})$ and a thief X is at point $(x, y)$. X has a constant velocity $V_x\hat{i} + V_y\hat{j} $, where $\hat{i}$ and $\hat{j}$ are unit vectors in ...
3
votes
2answers
170 views
Why is average velocity the midpoint of initial and final velocity under constant acceleration?
Since average velocity is defined as$^1$
$$\vec{\mathbf v}_\mathrm{av}=\frac{\vec{\mathbf x}-\vec{\mathbf x}_0}{t-t_0},$$
where $\vec{\mathbf x}$ denotes position, why is this quantity equal to
...
0
votes
0answers
47 views
Finding an efficient strategy for walking
Let's say you are already walking at a maximally efficient combination of pace and stride (or $\omega$ and $X_0$ I guess) but you need to reach your destination faster. Should you increase/decrease ...
0
votes
1answer
184 views
Solving inclined plane using diff. frame
I was trying to solve frictionless inclined plane problem using a diff. frame as shown in the figure, and can't figure out that acceleration along the plane = g.sin(Θ), but I think it should be = ...
1
vote
0answers
80 views
Kinematics algebra, pT, Peskin Eq.17.59
my question concerns the kinematics of 2 to 2 particle scattering. I refer to Peskin and Schroeder eq.17.59 going from this expression
...
0
votes
2answers
109 views
Negative sign of acceleration [closed]
This is the problem from our Physics textbook :
A player throws a ball upwards with an initial speed of 29.4 m s–1.
(a) Choose the x = 0 m and t = 0 s to be the location and time of the ball at ...
